The invention relates to the steam reforming of normally liquid hydrocarbons. This invention contemplates the use of a catalyst for the high temperature reaction between steam and normally liquid hydrocarbons (boiling in the naphtha range) to produce hydrogen and carbon oxides.
1. Field of the Invention
This invention relates to the provision of a catalyst which is essentially resistant to the deposition of carbon during the high temperature reaction of long chain hydrocarbons with steam to form carbon monoxide and hydrogen. The steam reforming reaction is well known and does not promote normally the deposition of carbon so long short chain hydrocarbons such as methane and ethane are utilized. However, when the naphthas are utilized as the feed material, a problem of deposition of carbon on the catalyst surfaces occurs. This invention provides a catalyst which is active for the reaction, but which does not promote deposition of carbon. This catalyst comprises nickel, promoted with the oxides of manganese and iron on a low surface area refractory support. The catalyst is characterized by the fact that the metallic constituents are not chemically combined with the refractory support and by the fact that the refractory support has a specific surface area.
2. Description of the Prior Art
The constituents comprising the catalyst of this invention have been known for many years as promoters and as catalytically active agents for reforming catalysts. The use of manganese, for example, was recognized as early as 1930 by Raymond Benner and Alfred Thompson of General Chemical Company as a strengthening and hardening constituent for activated bauxite as disclosed in their U.S. Pat. No. 1,778,517. The use of alkaline and alkaline earth metals in conjunction with nickel cobalt or iron group catalysts utilized in conjunction with carriers such as manganesium or aluminum oxide was disclosed as early as 1926 in British Pat. No. 267,535 to I. G. Farbinindustrie, A. G. Williams, of DuPont in U.S. Pat. No. 1,736,065 recognized the use of aluminum oxide, manganese oxide, potassium oxide and calcium oxide among others as promoters for the nickel catalyst utilized in the production of hydrogen by the reaction of steam and gaseous hydrocarbons. Incorporation of an alkali earth oxide into a catalyst comprising nickel and a fused alumino-silicate refractory was disclosed by Fremuth as early as 1934 in U.S. Pat. No. 1,970,695. More recently, Warshaw, et al., in U.S. Pat. No. 3,446,159 suggested the use of a manganese promoted nickel catalyst for the conversion of liquid hydrocarbons to methane. This catalyst was prepared by coprecipitation of alumina, nickel and manganese from a solution of their respective nitrates. The patent to Padovani, et. al., U.S. Pat. No. 3,205,182 in 1965 suggested a catalyst supported on a refractory support and comprising a metallic oxide which included the oxides of manganese and iron. However, in this case, Padovani required that the support and the metallic oxides be calcined at temperatures in the range of 1200 to 1400 degrees C. for 24 hours so as to react the oxides with the supports and therefore prevent blockage of the catalytically active nickel constituents subsequently incorporated onto the carrier. Taylor and Sinfeld in a series of U.S. Pat. Nos. 3,320,182; 3,394,086; 3,404,100; and 3,407,149, all of Esso Research and Engineering Company have shown the advantages of the various promoters and specifically the advantage of barium in relation to a catalyst for the production of a methane rich gas from naphtha. All of these catalysts, however, are of high surface area type. The patentees, for example, in U.S. Pat. No. 3,320,182, point out that barium produces the best activity maintenance of all the promoters utilized. Thus, for example, it was stated that barium reduced the surface area less, i.e., from 190 m.sup.2 /gm, unpromoted to 140 m.sup.2 /gm promoted, whereas potassium reduced the surface area from 190 to 110 m.sup.2 /gm. Essentially, the same catalyst, in U.S. Pat. No. 3,394,086 was utilized for the steam reforming of naphtha hydrocarbon to produce a hydrogen rich gas. However, this catalyst had a surface area from 100 to 300 m.sup.2 /gm and a nickel surface area of from 5 to 20 m.sup.2 /gm.